Shipping yards may be massive, covering many acres of land. Further, in yards such as rail yards, trailer yards or shipping yards, the yards may shift over time. They may overflow into adjacent areas, fields or parking lots. They may also shrink. Yards may grow out or up, and they may “move” over time, for example into lanes and alleys, parking locations may drift among other challenges.
One issue in managing yards of trailers or containers is locating the suitable trailer for the next load. Typically, yard managers know which trailers are empty or full based on yard location or memory, and they may direct a shunt driver to obtain an empty or full trailer and deliver it to the front of the yard to be ready for transport.
A shunt vehicle is basically a vehicle that can pick up a trailer or container and pull it or carry it to the front of the yard for dispatch.
One issue is that, upon being instructed to shunt a trailer or container, the target is often not at its specified location. Furthermore, location technologies such as GPS can be inaccurate by 10, 100 or even 1000 meters, depending on signal strength and power use of the GPS receiver.
If a shunt vehicle is dispatched to a location incorrectly, it may waste time. In the real world, in many cases the driver of the shunt vehicle can spend 15 to 30 minutes searching for a container or radioing back for a lost container. Further, for future autonomous vehicles, incorrect dispatching of such vehicle wastes fuel energy, adds traffic to the yard as well as wasting time for other dispatching jobs.